render with custom output types

[karelvaculik]

Hi, I was wondering if it would make sense to extend the render method to support other output types than uint8.
Specifically, render method of TFPyEnvironment converts all outputs into uint8.

I am aware that the type makes sense for plotting images (and render method is primarily designated for this purpose), but when I create a custom environment, I would like to be able to pass general array from the environment, e.g. an array of float32 values, and then print / plot it my way. Let's say I have quite a complex environment that produces observations with transformed values. Such observations are good to feed into agents (neural networks), but they are not useful for debugging / illustration when checking my agent on an eval environment. What's more important is that it's hard to convert the transformed values into a useful representation for humans. Therefore I thought I could use render method to fetch the observation in a "human-understandable" form (i.e. not transformed).

I noticed the note in docstring that the conversion into uint8 is due to compatibility reasons, but I believe it could be still extended (e.g. through a new parameter) in such a way that the default behaviour would satisfy this conversion to uint8 - to keep the compatibility intact.